Functional failures or manufacturability impairments of electronic components or assemblies are often attributable to damage caused by electrostatic discharge, electrostatic field force, electromagnetic radiation, moisture, oil and/or corrosive gases encountered during storage, shipment and/or processing. The problem has increased in severity in recent years, and will continue to worsen. The current trend in electronic devices and systems is towards miniaturization like VLSI (Very Large Scale Integration) chip technology. These smaller devices are more sensitive to corrosion and electrostatic damage. Yet, the demand for greater reliability is increasing. Accordingly, protection of electronic devices and systems is needed to preserve their functionality during storage, shipment and processing.
A packaging material for electrostatic discharge, electromagnetic radiation, and moisture-proof protection is disclosed by Mondano in U.S. Pat. No. 3,572,499. An aluminum foil moisture barrier, a heat-sealable carbon-filled polyethylene inner layer and a nonwoven protective outer layer are laminated together to form the Mondano packaging material. The carbon-filled polyethylene inner layer, however, will delaminate from the aluminum foil and absorb oil when contacted by oil. Additionally, excessive carbon will contaminate the parts enclosed in the package by carbon transfer and will degrade the heat seal seam strength if the layer contains carbon sufficient to achieve static-dissipative electrical surface resistivity of between 10.sup.5 and 10.sup.12 ohms per square. If the carbon loading in the polyethylene is reduced to obtain sufficient heat seal seam strength, the surface resistivity exceeds 10.sup.12 ohms per square and the inner surface of the package is no longer static-dissipative.
Thus, there is a need for an oil-resistant, heat sealable, humidity insensitive, electrostatic-dissipative material for packaging electronic devices and systems. It is an object of the invention to provide composites useful as heat-sealable, oil-resistant, low contamination, humidity insensitive, electrostatic-dissipative, flexible materials for packaging electrostatic discharge sensitive (ESDS) items such as microcircuits, sensitive semiconductor devices, sensitive resistors and associated higher assemblies.